Immunosuppressive medications are required to prevent graft rejection after organ transplantation. A major side effect of these drugs is an increased rate of infections. One of the major infections is cytomegalovirus (CMV) which can lead to hepatitis, gastritis, pneumonitis, and death. This infection is both treated and prevented with ganciclovir. In studies conducted partially at Indiana University, an oral formulation of ganciclovir was shown prevent CMV infection in liver patients. Although effective, only about 8% of the dose is absorbed necessitating high doses of the ganciclovir. In addition, although the levels obtained in the blood are adequate to prevent CMV they are not adequate to treat infection. A new derivative of ganciclovir, valganciclovir, has been developed that in preliminary studies in patients with HIV, has been found to achieve levels equivalent to intravenous ganciclovir with a smaller dose than the oral ganciclovir. If these results hold true in transplant patients, then fewer pills would be needed to prevent CMV, improving compliance, and CMV could be treated with an oral rather then intravenous drug, thereby reducing cost. The primary purpose of this study is to determine a dose of valganciclovir given once daily to liver transplant recipients that provides a ganciclovir exposure between that provided by intravenous ganciclovir given at 5 mg/kg/day and that provided by oral ganciclovir given at 3000 mg/day. This will be assessed by measuring ganciclovir phamacokinetics in the GCRC using an open label randomized 4-way crossover study. It is anticipated that 24 patients will be studied at 5 institutions.